Mini Tidal Waves
It has been the subject of many nightmares and worst-case scenarios. Giant waves have been slamming into the California coastline, sending massive surges of foaming water over seawalls, flooding streets, and dragging sand into the ocean. Coastal towns like Newport Beach and Manhattan Beach have faced water washing into neighborhoods, stranding vehicles, and forcing locals to stay far back from the water's edge. These colossal waves are not just a thrilling sight for surfers; they are a warning sign from nature. Understanding why these massive waves happen and why they are becoming more frequent requires looking closely at ocean science and climate change.
Waves are created when wind blows across the surface of open ocean waters. The harder the wind blows and the longer it pushes across the water, the larger the waves become. Out in the vast Pacific Ocean, severe weather systems, deep ocean storms, and offshore tropical weather push vast amounts of energy into the sea. This energy travels across hundreds of miles of ocean as deep swells until it reaches shallow coastal waters. When a ocean swell hits the shallow seabed near beaches and cliffs, the water slows down at the bottom and arches up at the top, creating towering waves that crash onto the shore with immense force…
While giant ocean swells have always occurred naturally, ocean scientists have found that wave heights along the Pacific Coast are steadily increasing. Studies analyzing ocean energy over decades show that average winter wave heights off the coast of California have grown significantly over the past half-century. The force behind these larger swells is directly connected to, you guessed it, human-caused climate change!
As human activities burn fossil fuels like coal, oil, and gas, heat-trapping greenhouse gases accumulate in Earth's atmosphere. This extra warmth gets trapped inside the Earth system, and the oceans absorb over ninety percent of that excess heat. Warmer atmospheric temperatures lead to warmer ocean water, which acts as fuel for coastal storms. Warmer oceans heat the air directly above them, causing atmospheric pressure differences that create stronger, faster winds across the open sea. Stronger winds blow harder across the water, transferring much more energy to the surface and pushing ocean swells into higher and more powerful waves.
At the same time, global warming causes glaciers and polar ice sheets to melt, while warm ocean water naturally expands. Together, these processes cause sea levels around the globe to rise. Rising sea levels change how waves interact with coastal towns. In the past, a massive wave might break harmlessly on the sandy beach. Today, because baseline water levels are higher, those same giant waves start closer to human structures. They ride in on top of elevated sea levels, carrying enough water to easily overtop ocean barriers, erode beaches, flood city streets, and damage homes.
This combination of rising sea levels and stronger storms creates a compounding effect that scientists call ‘coastal flooding chaos.’ When high tide aligns with powerful storm swells, the water has nowhere to go but inland. The water rushes up boardwalks, damages piers, knocks over beach infrastructure, and washes away delicate beach habitats. What used to be a rare event that happened once every few decades is gradually turning into a recurring seasonal hazard for people living along the coast.
Climate science helps explain these pounding ocean waves not as isolated weather events, but as a direct symptom of a warmer planet. Ocean waters and global climate systems are interconnected. Warmer air creates stronger storm winds, stronger winds generate higher waves, and higher sea levels allow those giant waves to reach further into coastal communities.
But we are a resilient species. To protect coastal towns in the future, engineers, scientists, and local leaders are searching for new ways to adapt. Communities are building stronger seawalls, restoring natural sand dunes that act as sponges for ocean energy, and planning smarter development away from flood zones. The big waves crashing into California serve as a powerful reminder of how connected our ocean, atmosphere, and everyday communities truly are, highlighting the importance of understanding climate science to keep coastal areas safe.